1. Field of the Invention
The present invention relates to an injection device particularly suitable for the intraruminal injection of medicaments, as fluid solutions or suspensions, to ruminants. More particularly, the invention relates to an injection device having needle actuation means and dose delivery actuation means which substantially eliminate the possibility of administering a dose to a host animal outside of the intended dose delivery area.
2. State of the Art
Numerous automatically actuable injection devices have been described in the prior art, as for example in U.S. Pat. Nos. 3,016,897; 3,051,173; 3,064,650; 3,114,370; 3,141,583; 3,430,626; 3,494,358; 3,677,246; 3,727,614; and 3,809,083. While the prior art devices typically provide for actuation of the injection device when the injection device is brought into contact with the surface of a host to be injected, they are not concerned with the spatial orientation of the surface being injected and the injection device itself, which controls the ultimate site at which delivery of the injection dose will occur. In instances where it is desirable to inject a medicament dose into a particular body cavity of a host or at a particular intramuscular layer within the host, it is of primary importance to control the direction at which the injection device enters the host animal and the spatial orientation of the injection surface and the injection delivery system. An example of such an instance of use is the direct injection of medicaments, e.g. anthelmintics, into the rumen of a ruminant, such as cattle, sheep and the like. For each particular ruminant the general location of the rumen is known and by an appropriately directed injection through the outer skin layer, injections can be made directly into the rumen. However, in order to ensure insertion of the needle into the rumen, the orientation of the injecting instrument with respect to the host animal must be controlled prior to injection. Thus, there is a need to prevent the actuation of the injection mechanism unless the injection delivery system is in a proper orientation with respect to the injection surface of the host animal, and also to prevent delivery of the medicament dose unless the injection apparatus is positioned appropriately within the host.